Is rc 70 too hard?

D

DavidL41

Joined
Oct 12, 2014
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Is there a such thing as an rc 70 or rc 80 knife? If not is the extra hardness not useful? what rc do 300 dollar knives use?
 
That sounds like the hardness of a ceramic knife. That hardness is too high for a normal steel. DM
 
A high Rockwell hardness isn't always optimal. For example, if a knife is heat treated to a Rockwell hardness that is too high for the steel, the edge may chip during cutting.
 
CPM-Rex121 blade can reaches 72RC.

Extra hardness + sufficient toughness = good knives. Super hard Ceramic/diamond/glass knives have limited usability, which is a small sub set of practical usage.

Price has very little correlation with hardness. Price mostly goes with quality & art & perceive value & of course what ppl willing to pay.

DavidL41 said:
Is there a such thing as an rc 70 or rc 80 knife? If not is the extra hardness not useful? what rc do 300 dollar knives use?
Click to expand...
 
Optimum hardness depends on the type of steel used. If there is anything as hard as 70-80, I've not heard of it. I believe (someone correct me if I'm wrong) Cowry X can reach 66-68. Some of the super steels can reach 62-64.

Also, other factors determine your target hardness. Do you want edge retention? Do you want toughness? Do you care if sharpening is more/less difficult?
 
bluntcut said:
CPM-Rex121 blade can reaches 72RC.

Extra hardness + sufficient toughness = good knives. Super hard Ceramic/diamond/glass knives have limited usability, which is a small sub set of practical usage.

Price has very little correlation with hardness. Price mostly goes with quality & art & perceive value & of course what ppl willing to pay.
Click to expand...

I forgot about REX-121...
 
I was quoted 85 dollars for a knife for leather working. RC 60. 154cm steel. http://www.knipknives.com/leather.php

The knife I have now is made by the same person, same steel and does a good job. Looking for something beyond that that wont need as much sharpening and stay sharp longer.

For a 40 more dollars I may go for the RC70 REX 121 if its possible to get it for that price - single blade 10 cm long 2 cm at the thickest part, full tang.
 
CPM154 at 62-63rc will be a much better leather knife than cpm-rex121/s110v/s90v/etc... because cpm154 fine grain & carbide offers whisper quiet cut and plenty good edge retention. Note: high alloy knives will be harder to sharpen and lower toughness. There are many carbon & semi-stainless knives with good ht at high hardness also be good leather knife too. Keep in mind that wrong edge geometry can lead to quicker dulling since leather contain nano-size silicates, which can burnish and or abrade the edge.

DavidL41 said:
I was quoted 85 dollars for a knife for leather working. RC 60. 154cm steel. http://www.knipknives.com/leather.php

The knife I have now is made by the same person, same steel and does a good job. Looking for something beyond that that wont need as much sharpening and stay sharp longer.

For a 40 more dollars I may go for the RC70 REX 121 if its possible to get it for that price - single blade 10 cm long 2 cm at the thickest part, full tang.
Click to expand...
 
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